In an inserting machine for mass mailing, there is a gathering section where the enclosure material is gathered before it is inserted into an envelope. This gathering section is sometimes referred to as a chassis subsystem, which includes a gathering transport with pusher fingers rigidly attached to a conveying means and a plurality of enclosure feeders mounted above the transport. If the enclosure material contains many documents, these documents must be separately fed from different enclosure feeders. After all the released documents are gathered, they are put into a stack to be inserted into an envelope in an inserting station. Envelopes are separately fed to the inserting station, one at a time, and each envelope is placed on a platform facing down with its flap flipped back all the way. At the same time, mechanical fingers or vacuum suction device are used to keep the envelope on the platform while the throat of the envelope is pulled upward to open the envelope. The stack of enclosure material is than automatically inserted into the opened envelope.
Before the envelope is spread open, a number of suction cups must be properly positioned at the throat of the envelope. The position of suction cups, relative to each other, must be adjusted in accordance with the size and the type of the envelope. FIG. 1A and FIG. 1B illustrate the different envelope sizes that require different placement of the suction cups in order to properly lift the throat of the envelope. In FIG. 1A, there is shown a small envelope 100 having a relatively large flap 102 and a deep throat 104. In FIG. 1B, there is shown a large envelope 100 having a relatively shallow throat 104. Where four suction cups are used to lift the throat 104 at four pickup points A, B, C, D to spread open the envelope, it is preferred that the pickup points A, B, C, D be evenly spaced around the throat 104. In FIG. 1A, the pickup points A, B, C, D spread out more in the Y direction because of the deep throat 104. But in FIG. 1B, the pickup points A, B, C, D spread out more in the X direction because of the width, W, of the envelope. The distance between two adjacent suction cups can be, for example, determined by EQU X.sub.2 =(W-2X.sub.1)/3 EQU Y.sub.2 =X.sub.2 tan.alpha.
where .alpha. is the slope angle of the throat 104 and X.sub.1 and Y.sub.1 can be a distance ranging from 0.3" to 0.6" (7.6 mm to 15.2 mm).
It is, therefore, desirable to have an envelope opening device wherein the associated suction cups can be adjusted to match a wide range of envelope sizes and throat configurations.